Coated articles are known in the art for use in window application such as insulating glass (IG) window units, vehicle windows, and/or the like. In certain situations, designers of coated articles often strive for a combination of high visible transmission, substantially neutral color, low emissivity (or emittance), and blockage of undesirable radiation such as infrared (IR) and/or ultraviolet (UV) radiation to prevent undesirable heating or damage to a building or vehicle interior, or the like. Moreover, in certain example non-limiting instances, it is desirable to heat treat (HT) such coated articles (e.g., thermally temper, heat bend, and/or heat strengthen). Such heat treating often involves exposing the coated articles to temperatures of at least about 580 degrees C., more typically at least about 600 or 625 degrees C. which can lead to undesirable damage to many coatings.
Heat resistant UV blocking coatings deposited by wet chemistry techniques are known in the art. Such UV blocking coatings deal with the use of cerium oxide as the UV blocking material. Cerium oxide is an efficient UV blocker. However, unfortunately, cerium oxide absorbs significant amounts of light in the visible range thereby decreasing visible transmission of coated articles in which it is used, especially when combined with titanium oxide. For this reason, the use of cerium oxide in coated articles for windows or the like is not very desirable in certain applications. Furthermore, because of their high refractive index (n), thin films of cerium oxide provided directly on glass substrates also exhibit undesired optical effects such as interference colour etc. In order to suppress these undesired optical effects, an inner layer of a lower index material may be used. In addition to the drawbacks associated with the optical performance of cerium oxide based UV blocking coatings, fabrication of such coatings by vacuum deposition process is difficult and not attractive to commercial manufacturing applications.
In view of the above, it will be appreciated that there exists a need in the art for a heat resistant UV blocking coating that may be manufactured by high volume vacuum deposition processes such as sputtering. In certain example instances, it would also be desirable to provide UV blocking coatings that are heat resistant and are capable of achieving enhanced optical performance through thin film designs.